[TUHS] margins and indenting, and arbitrary c rules

Noel Chiappa jnc at mercury.lcs.mit.edu
Fri Nov 10 01:09:36 AEST 2017


    > From: Steve Simon

    > At the risk of stirring up another hornets nest...

I usually try not to join in to non-history threads (this list has too much
random flamage on current topics, IMNSHO), but I'll make an exception here...

    > this means my code is usually fairly narrow.

I have what I think are somewhat unusual thoughts on nesting depth, etc, which
are: keep the code structure as simple as possible. That means no complex
nested if/then/else structures, etc (more below).

I'd been moving in this direction for a while, but something that happened a
long time ago at MIT crystalized this for me: a younger colleague brought me a
routine that had a complex nested if/etc structure in it, which had a bug; I
don't recall if he just wanted advice, or what, but I recall I fixed his
problem by..... throwing away half his code. (Literally.)

That really emphasized to me the downside of complexity like that; it makes it
harder to understand, harder to debug, and harder for someone else (or you
yourself, once you've been away from it for a while) to modify it. I've been
getting more formal about that ever since.


So, how did I throw away half his code? I have a number of techniques. I try
not to use 'else' unless it's the very best way to do something. So instead
of:

    if (some-conditional) {
       <some code>;
       }
      else {
       <some other code>;
       }      

(iterated, recursively) do:

    if (some-conditional) {
       <some code>;
       xxx;
       }

    <some other code>;

where xxx is a 'return', or a 'break', or a 'continue'. That way, you can
empty your brain once you hit that, and start with a clean slate.

This is also an example of another thing I do, which is use lots of simple
flow-control primitives; not go-tos (which I abhor), but loop exits, restarts,
etc. Again, it just makes things simpler; once you hit it, you can throw away
all that context/state in your mind.


Keep the control flow structure as simple as possible. If your code is several
levels of indent deep, you have much bigger problems than fitting it on the
screen.


I wrote up a complete programming style guide for people at Proteon working on
the CGW, which codified a lot of this; if there's interest, I'll see if I can
find a copy (I know I have a hardcopy _somewhere_).

     Noel


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